Cutting performance and wear characteristics of Ti(C,N)-based cermet tool in machining hardened steel

Cutting performance and wear characteristics of Ti(C,N)-based cermet was investigated when turning a hardened steel (61-62 HRC). A TiN/Al2O3/Ti(C,N) multilayer coated cemented carbide tool was selected for this comparable study. The cermet tool showed a longer tool life than the coated tool at lower cutting depth, but it showed a shorter tool life at larger cutting depth due to chipping caused by increasing cutting force. Soft binder phase in the flank face of the cermet tool was removed primarily by abrasion and adhesion wear mechanism, and then ceramic grains were removed due to lack of structural support. High thermal conductivity and low cutting force appeared to improve the crater wear resistance of the cermet tool. But the coated tool suffered very severe crater wear due to diffusion and adhesion wear mechanisms. The surface quality machined by the cermet tool was slightly lower than that by the coated tool and the average roughness increased exponentially with the cutting time for both tools. Thermal stress that generated at the chips during the cutting process forced the chips to curl. The chips from the cermet tool showed less severely curled and adhesive due to the low cutting temperature.